Rewrite ${((7^{10})(5^{-7}))^{-4}}$ in the form ${7^n \times 5^m}$.
Solution: ${ ((7^{10})(5^{-7}))^{-4} = (7^{(10)(-4)})(5^{(-7)(-4)})} $ ${\hphantom{ ((7^{10})(5^{-7}))^{-4}} = 7^{-40} \times 5^{28}} $